21980 Sigma-Aldrich


for microscopy

Synonym: Foxgreen, IC Green, Indocyanine green

  • CAS Number 3599-32-4

  • Empirical Formula (Hill Notation) C43H47N2NaO6S2

  • Molecular Weight 774.96

  •  Beilstein Registry Number 4115884

  •  EC Number 222-751-5

  •  MDL number MFCD00013078

  •  PubChem Substance ID 329752231



Related Categories Analytical Reagents, Analytical/Chromatography, Microscopy Reagents, Stains and Dyes
grade   for microscopy


Other Notes

A diagnostic aid in the determination of hepatic function


Bottomless glass bottle. Contents are inside inserted fused cone.


Cardiogreen was injected in animals intravenously for dynamic optical imaging system to study the capability of capturing the in vivo biodistribution kinetics.

General description

Cardiogreen is a dye used for microscopy. This dye has its maximum extinction at the same wavelength as reduced and oxygenated haemoglobin meet making it possible to record the oxygen saturation in blood. This dye has no side-effects.

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
Precautionary statements 
Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 

Frequently Asked Questions

How does the storage temperature relate to shipping conditions?
The storage conditions that a Sigma-Aldrich catalog and label recommend for products are deliberately conservative. For many products, long-term storage at low temperatures will increase the time during which they are expected to remain in specification and therefore are labeled accordingly. Where short-term storage, shipping time frame, or exposure to conditions other than those recommended for long-term storage will not affect product quality, Sigma-Aldrich will ship at ambient temperature. The products sensitive to short-term exposure to conditions other than their recommended long-term storage are shipped on wet or dry ice. Ambient temperature shipping helps to control shipping costs for our customers. At any time, our customers can request wet- or dry-ice shipment, but the special handling is at customer expense if our product history indicates that the product is stable for regular shipment. See Shipping and Storage for more information.
Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
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What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
Has Cardiogreen been used for in vivo optical imaging studies?
We do not subject this product to in vivo testing. However, one study documents the use of the product in a study with mice:For optical imaging, mice were injected intravenously with a mixture of 0.05 ml of 260 μM ICG (Cardiogreen) and 0.05 ml of 360 μM DTR (70,000 MW, Invitrogen) in saline (equivalent to 0.4 mg per kg or 7.4 μM initial concentration in blood).
Does Cardiogreen dissolve equally well in saline and in water?
Each lot is tested for solubility in hot water at 1 mg/mL. We have found that Sigma Product No. I2633 (which has the same CAS number as Product No. 21980) dissolves in water at 1 mg/mL without heating. Further dilute in saline to prepare an isotonic solution.
How long can I store a solution of Cardiogreen after it has been prepared?
Sigma-Aldrich recommends that solutions be prepared fresh and not stored. Solutions "are stable only for a few hours and cannot be kept overnight." See: Sigma-Aldrich Handbook of Dyes, Stains, and Indicators, Green, F. ed., p. 407.
Can Product No. I2633, Cardiogreen, be used as a biological stain?
Limited absorbance in the visible region practically precludes the use of Indocyanine Green as a biological stain. See: Sigma-Aldrich Handbook of Dyes, Stains, and Indicators, Green, F. ed., p. 407.
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